1. Field of the Invention
The present invention relates to a semiconductor device bonded by a so-called flip-chip mounting method, a process for producing the same, and an adhesive sheet to be used for adhering a semiconductor chip or a semiconductor wafer and a substrate to produce the same.
2. Description of the Related Art
In recent years, in terms of a semiconductor integrated circuit (IC) getting more integrated and semiconductor device (IC package) getting more compact, etc., a flip-chip mounting method has come to be applied. The flip-chip mounting method is a kind of a wireless bonding method including the steps of forming bumps made by soldering, etc. on electrodes on a surface of the semiconductor chip, mounting the semiconductor chip made to be upside down on a print substrate, ceramic substrate or other substrates, aligning the bumps with the electrodes on the substrate, then, heating to fuse the bumps so that the electrodes of the semiconductor chip and the electrodes of the substrate are bonded.
In a semiconductor device made by the above flip-chip mounting method, a resin called an under filling material is generally provided between the semiconductor chip and the substrate to prevent crack, etc. caused by a difference of coefficients of linear expansion between the semiconductor chip, the bumps and the substrate.
As the under filling material, a liquid epoxy resin composition obtained by blending an epoxy resin, curing agent and inorganic filler is normally used. The liquid epoxy resin composition is hardened after being injected into a space between the semiconductor chip and the substrate.
Recently, rapid progress has been made along with higher integration of a semiconductor integrated circuit, such as multi-electrodes, narrower pitches between electrodes, and the semiconductor device getting thinner, so spaces between the bumps are becoming extremely narrow and a distance between the semiconductor chip and the substrate is becoming extremely short. When the spaces between bumps become extremely narrow and the distance between the semiconductor chip and the substrate becomes extremely short as above, it becomes hard for the under filling material to get into the space between the semiconductor chip and the substrate (between the bumps) due to a flow resistance. Then, the under filling material hardens in a state it is not sufficiently spread out in the space between the semiconductor chip and the substrate, and when there arises a deficiency in the under filling material, the quality of a resulting semiconductor device decreases.